Hamburg 2001 – scientific programme

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DS: Dünne Schichten

DS 31: Postersitzung

DS 31.14: Poster

Tuesday, March 27, 2001, 16:30–17:30, Foyer Saal 4

IN SITU INVESTIGATION OF AlAs/GaAs INTERFACES DURING ION IMPLANTATION AT 15 K — •E. Wendler, W. Wesch, and B. Breeger — Friedrich-Schiller-Universität Jena, Institut für Festkörperphysik, Max-Wien-Platz 1, 07743 Jena

Ion implantation and Rutherford backscattering spectrometry were performed in situ at 15 K without temperature change between implantation and measurement. N, Ar and Xe ions were implanted into AlAs/GaAs and GaAs/AlAs heterostructures to study the damage formation at the interface between the two materials. Mesurements with 1.4 MeV He ions and a backscattering angle of 110^o result in an improved depth resolution. The thickness of the affected GaAs adjacent to the AlAs was found to be about 20 nm nearly independent on ion species and ion fluence. This suggests that defects are mobile within the collision cascades even at temperatures as low as 15 K. In AlAs an ion-beam-induced interfacial amorphisation starts from the adjacent amorphised GaAs. At low concentrations of the implanted ions the amorphisation proceeds proportional to the total number of lattice displacements per unit volume, but with a higher rate at the AlAs/GaAs interface than at the GaAs/AlAs interface. The amorphisation mechanism changes into an ion-controlled process after a critical ion concentration is exceeded, corresponding to the amorphisation mechanism found in bulk AlAs without interfaces to GaAs.